The use of various types of semi-rigid, thermoplastic containers for storing and transporting food items is well known. An example of one suitable type of container is provided in U.S. Pat. No. 6,170,696, herein incorporated by reference in its entirety. A container of this design is relatively inexpensive and therefore can be readily disposed of after use without causing a significant monetary outlay. However, this container is also specially adapted for improved durability and sealing and may further be microwavable, freezable, and dishwasher safe. Hence, the container of the disclosed type is much more versatile and may be reused for at least a limited time.
Typically, containers of both the aforementioned type and other types include both a base portion defining a cavity or storage area and a cover portion attachable to the base to open and close the storage area. To physically attach and detach the base and cover, both the base and cover include engageable closure portions extending about their peripheral edges. It is important that engagement between the closure portions be sufficiently secure so that unintentional detachment of the cover from the base is prevented. To preserve the food items and prevent spillage, it is furthermore important that the closure portions engage in such a manner as to create a sufficiently leak-free seal. However, it is also desirable that engagement of the closure portions occur without great difficulty or require excessive effort.